It is known to add hardened elastomer crumb material, generally elastomer waste material, as filler to elastomer starting materials before they are hardened. In this way, the hardened elastomer waste material, for which otherwise there would be hardly any use, can be reused in an appropriate manner.
The elastomer waste material is here comminuted, for example, in a cutting mill to produce a fraction of different grain sizes, with the major portion being particles of a size larger than 1 mm and a small percentage of dust is also processed as a non-damaging admixture.
In this way, it is possible to produce, for example, casings for circular struts in conveyor systems in which the adhesive behavior of such an elastomer casing is appreciated. Such casings are produced in an extrusion process and the fractionated ground material is added to the starting material for such an extrusion process in a manner similar to the admixture of a filler. The extruded product is then, for example, a tube composed of the admixed, already hardened particles which are encased in the original starting material so as to form a rough, non-smooth surface in the finished, vulcanized end product.
The drawback of this type of manufacture is that many particles are used which are too large and form coarse raised portions on the surfaces of the finished product that adversely influence the sliding behavior.